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>12.3. Selecting the backup tool</A
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><P
> There are many tools that can be used to make
	backups.  The traditional UNIX tools used for backups
	are <B
CLASS="COMMAND"
>tar</B
>, <B
CLASS="COMMAND"
>cpio</B
>, and
	<B
CLASS="COMMAND"
>dump</B
>.  In addition, there are large number
	of third party packages (both freeware and commercial) that
	can be used.  The choice of backup medium can affect the choice
	of tool.  </P
><P
> <B
CLASS="COMMAND"
>tar</B
> and <B
CLASS="COMMAND"
>cpio</B
> are
	similar, and mostly equivalent from a backup point of view.
	Both are capable of storing files on tapes, and retrieving
	files from them.  Both are capable of using almost any media,
	since the kernel device drivers take care of the low level
	device handling and the devices all tend to look alike to user
	level programs.  Some UNIX versions of <B
CLASS="COMMAND"
>tar</B
>
	and <B
CLASS="COMMAND"
>cpio</B
> may have problems with unusual files
	(symbolic links, device files, files with very long pathnames, and
	so on), but the Linux versions should handle all files correctly.
	</P
><P
> <B
CLASS="COMMAND"
>dump</B
> is different in that it reads
	the filesystem directly and not via the filesystem.  It is
	also written specifically for backups; <B
CLASS="COMMAND"
>tar</B
>
	and <B
CLASS="COMMAND"
>cpio</B
> are really for archiving files,
	although they work for backups as well.  </P
><P
> Reading the filesystem directly has some advantages.
	It makes it possible to back files up without affecting their time
	stamps; for <B
CLASS="COMMAND"
>tar</B
> and <B
CLASS="COMMAND"
>cpio</B
>,
	you would have to mount the filesystem read-only first.
	Directly reading the filesystem is also more effective, if
	everything needs to be backed up, since it can be done with
	much less disk head movement.  The major disadvantage is that
	it makes the backup program specific to one filesystem type;
	the Linux <B
CLASS="COMMAND"
>dump</B
> program understands the ext2
	filesystem only.  </P
><P
> <B
CLASS="COMMAND"
>dump</B
> also directly supports
	backup levels (which we'll be discussing below); with
	<B
CLASS="COMMAND"
>tar</B
> and <B
CLASS="COMMAND"
>cpio</B
> this has to
	be implemented with other tools.  </P
><P
> A comparison of the third party backup tools is beyond
	the scope of this book.  The Linux Software Map lists many of
	the freeware ones.  </P
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